This application claims priority from Korean Patent Application No. 2000-30089, filed Jun. 1, 2000, the entirety of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates in general to a method for the fabrication of a capacitor of a semiconductor memory device, and more particularly to a method of fabricating a capacitor of a semiconductor device, which is capable of increasing a charge storage capacitance of the capacitor while preventing generation of leakage current in the capacitor.
2. Description of the Related Art
With recent advances in semiconductor fabrication technology, the demand for memory devices had increased rapidly. In semiconductor devices, a capacitor being used as a data storage element is varied in its capacitance depending on the area of its electrodes, the distance between the electrodes, and the dielectric constant of the dielectric film interposed between the electrodes.
However, as the integration density of a semiconductor device is increased, the capacitor is reduced in the area that it occupies in the semiconductor device and thus is the area of its electrodes is reduced, thereby reducing its capacitance.
For this reason, to maximize the capacitance of the capacitor, the prior art includes depositing a ruthenium film as the lower electrode on a substrate, depositing a TaON film having high dielectric constant on the ruthenium film, and depositing a metal film on the dielectric film, thereby forming a capacitor structure of metal film-dielectric film-metal film (MIM).
FIGS. 1a and 1b show a fabricating method of a capacitor of a semiconductor device according to the prior art. As shown in FIG. 1a, on a semiconductor device 2 having a MOS transistor (not shown), there is formed an interlayer insulating film 4 having a contact hole (not shown) through which one of junction regions of the MOS transistor is exposed.
After this, a polysilicon film 5 for a plug is filled in the interlayer insulating film 4, and then etched back to remove a native oxide film. Then, a Ti/TiN film 6 as a barrier metal film is deposited on the resulting substrate.
Afterwards, as shown in FIG. 1b, a ruthenium film 7 as a lower electrode is deposited on the barrier metal film 6 using an O2 gas as a reaction gas. The O2 gas used in this step makes the deposition of the ruthenium film 7 easy by breaking down the molecular structure of tris(2,4-octanedionato)ruthenium used as a ruthenium source.
Then, a TaON film 8 having a good dielectric constant is formed on the ruthenium film 7. Next, an upper electrode 9 is formed on the TaON film 8 to complete a capacitor of a semiconductor memory device.
However, such a prior method for the fabrication of the capacitor suffers from problems as described below.
The prior method employs the O2 gas in deposition of the ruthenium film as the lower electrode. This O2 gas makes deposition of the ruthenium film 7 easy by breaking down the molecular structure of tris(2,4-octanedionato)ruthenium as a ruthenium source, but causes carbons to remain in the ruthenium film, thereby deteriorating electrical properties of the resulting capacitor.
Thus, in order to remove carbons present in the ruthenium film and improve properties of the ruthenium, the prior art performs a subsequent heat-treatment, such as Rapid Thermal Processing (RTP), under an atmosphere of N2, Ar or Ar/N2. This results in loss in fabricating time and economical efficiency.
The present invention solves prior problems as described above and provides a fabricating method of a capacitor of a semiconductor device, which can improve electrical properties of the capacitor.
Additionally, the present invention provides a fabricating method of a capacitor of a semiconductor memory device, which is capable of increasing a charge storage capacitance of the capacitor while preventing generation of leakage current in the capacitor.
In one embodiment, the present invention provides a method for the fabrication of a capacitor of a semiconductor device, comprising the steps of forming a ruthenium film as a lower electrode on a semiconductor substrate; forming a TaON film having a high dielectric constant on the ruthenium film; and forming an upper electrode on the TaON film.
In another embodiment, the present invention provides a method for the fabrication of a capacitor in a semiconductor device, comprising the steps of forming a ruthenium film as a lower electrode on a semiconductor substrate; forming an amorphous TaON film having a high dielectric constant on the ruthenium film; annealing the amorphous TaON film to form a crystalline TaON film; and forming an upper electrode on the crystalline TaON film.